1. Nature of the Invention
The invention is concerned with grease compositions. More particularly it is concerned with a grease composition comprising oil, hydroxy-containing soap thickener and borated alkoxylated amides and, optionally, phosphorus and sulfur moieties.
2. Prior Art
U.S. Pat. No. 4,389,322 discloses the use of borated adducts of ethoxylated amides as a component of lubricating oils or greases. U.S. Pat. No. 4,389,322 is incorporated herein by reference.
The borated adducts of ethoxylated amides are prepared from ethoxylated compounds having the following generalized structure: ##STR1## R is a hydrocarbyl group having from about 1 to about 60 (preferably 8 to 30) carbon atoms; R may be alkyl, alkenyl, aralkyl, alkylaryl, etc; x and y may be the same or different and are each a whole number from 0 to about 15, preferably 1 to 5, but the sum of x and y must equal 1 or more, or more preferably, 2 or more. R.sup.4 is hydrogen or an alkyl or alkenyl radical of one to six carbon atoms and preferably is hydrogen or a methyl radical.
The borated derivatives can be prepared according to the disclosure in U.S. Pat. No. 4,490,256 which is incorporated herein by reference or by treating the described amides with boric acid optionally in alcoholic solvents such as butanol or pentanol, or optionally hydrocarbon solvents such as benzene, toluene, xylene or mixtures thereof. Reaction temperatures of 70.degree. to 260.degree. C. can be used but 110.degree. to 170.degree. C. is preferred. Reaction times can be 1 to 10 hours or more. Up to a stoichiometric amount or an excess of boric acid can be used to produce a derivative containing 0.05% to 8% or more by weight of boron. Other methods are also available to make similar borated derivatives. For example, the ethoxylated amides may also be borated through transesterification with a trialkyl borate such as tributyl borate (often in the presence of boric acid).
The publication "Manufacture and Application of Lubricating Grease" by C. J. Boner (Reinhold Publishing Company) 1954, pp. 155 and 436, 437 disclose the use of lithium soaps in grease making. The publication "Lubricant Additive" by C. V. Smalheer et al (Leyuis-Hiles Co.) 1967, pp. 1-11, discloses the use of phosphonates and thiophosphonates as additives in lubricants. "Condensed Chemical Dictionary" 9th Edition, (Van Nostrand Reinhold Company) at pages 520 and 938 discloses the use of lithium hydroxystearate in grease making and zinc dialkyldithiophosphate as a lube oil additive.
So far as is known, no effort has been made to employ borated alkoxylated amides in conjunction with a metal hydroxy-containing soap thickener and phosphorous-sulfur compounds. No prior art is known that teaches or suggests the unexpected results obtained by combining the known additives mentioned herein with the particular hydroxy-containing thickener and the borated alkoxylated amides as disclosed herein.